(Washington Post) – When it comes to combating climate change, many scientists and policy makers focus on one major goal: cut carbon emissions enough to keep the planet’s average surface temperature from rising more than 2 degrees Celsius above its pre-industrial level.

For years, the 2-degree target has been touted by experts as a kind of climate threshold: By staying within its confines, many argue, we can keep the planet in relatively stable condition and avoid the most dire effects of global climate change.

Currently, world leaders are developing concrete emissions reduction goals in preparation for this December’s U.N. climate change conference in Paris, where they’ll ultimately draft an international agreement to combat climate change with the goal of staying within the 2-degree mark. By contrast, if world nations were to do nothing — in other words, if we stuck to a “business as usual” trajectory — experts believe our climate could warm more than 4 degrees by the end of the century.

Three of the most heavy-hitting emissions reduction targets have already been declared by the United States, the European Union and China. The United States has resolved to reduce its carbon emissions by 26 to 28 percent below its 2005 emissions levels by 2020, and the European Union has vowed that by 2030 it will collectively cut its emissions by 40 percent compared to its 1990 levels. Meanwhile, China has claimed its carbon emissions will peak by 2030.

But according to the Grantham report, these resolutions, combined with the rest of the world’s projected future emissions, will probably not be enough to keep Earth within the 2-degree boundary.

“In thinking about where we’re going, it’s important to have an assessment now of what the sum total of those commitments might add up to,” said co-author Nicholas Stern, chair of the Grantham Research Institute on Climate Change and the Environment and president of the British Academy.

Stern and his co-authors Rodney Boyd and Bob Ward, also of the Grantham Research Institute, calculated what global greenhouse gas emissions will be in 2030 based on the announced targets from the United States, the European Union and China, as well as energy use estimates for the rest of the world published by the International Energy Agency (IEA). Then, they compared these calculations with a report from United Nations Environment Programme (UNEP) describing the kinds of emissions pathways that might allow the world to reach its 2-degree target.

The authors found that if the United States, the European Union, and China stick to their resolutions, their combined emissions in the year 2030 will be between 20.9 and 22.3 gigatons of carbon dioxide equivalent. (A gigaton is a billion metric tons.) And their estimate for the rest of the world’s emissions came to about 35.4 gigatons, meaning total global greenhouse gas emissions in 2030 could exceed 57 gigatons.

But according to the UNEP report the authors used for comparison, global emissions in 2030 must be below 48 gigatons if we want even a 50 percent chance of hitting the 2-degree mark. (What matters is not precise emissions in 2030, but rather what emissions pathway the world is on by then, with emissions in 2030 taken as a representation of that.)

In other words, on our current trajectory, we’re unlikely to make it. [more]

4 May 2015 (Grantham Institute) – Countries should seek ways to increase the ambition of their national pledges for reductions in greenhouse gas emissions, both before and after the crucial United Nations climate change summit in Paris in December, according to a paper published today (PDF) (4 May 2015) by the Grantham Research Institute on Climate Change and the Environment and the ESRC Centre for Climate Change Economics and Policy at London School of Economics and Political Science.

The call for greater action is based on an analysis by Rodney Boyd, Nicholas Stern, and Bob Ward which shows that the emissions in 2030 that have already been signalled by some of the largest-emitting countries, along with assumptions about current and planned policies by other countries, mean that it is unlikely that the aggregate pledges made by all countries ahead of the Paris summit will collectively be consistent with the goal of limiting the rise in global average temperature to no more than 2°C.

Depending on what assumptions are made about when China’s annual emissions of greenhouse gases will reach their peak, the European Union, United States and China are calculated together to be likely to emit between 20.9 and 22.3 billion tonnes of carbon-dioxide-equivalent in 2030.

Recent estimates by the United Nations Environment Programme indicate that pathways that are consistent with a 50-66% chance of limiting global warming to less than 2°C, without depending on negative emissions technology, have annual emissions of between 32 and 44 billion tonnes of carbon dioxide-equivalent in 2030.

This means either that the pledges put forward by the rest of the world (i.e., not including the European Union, United States and China) could not exceed emissions of about 23 billion tonnes in 2030, or that the collective emissions of the European Union, United States and China would have to be substantially lower than currently indicated. However, current and planned policies suggest that emissions by the rest of the world could be about 35 billion tonnes. It seems unlikely that the pledges from all countries before the Paris summit will collectively be sufficient to bridge the gap to an emissions pathway that is consistent with the limit of 2°C.

The paper states: “We think that it is important to offer a preliminary analysis of how the pledges and announcements by some of the biggest emitters, together with assumptions about current and planned policies by other countries, compare against pathways for staying within the global warming limit of 2°C. This allows us to confirm that there is a gap between the emissions pathway that would result from current ambitions and plans, and a pathway that is consistent with the global warming limit of 2°C. Consequently, countries should be considering opportunities to narrow the gap before and after the Paris summit.”

The paper concludes: “The ambitions and plans agreed at the Paris summit in December 2015 should be regarded as a critical initial step. It is also important that countries make pledges that are credible. However, the magnitude of the gap between current intentions and the international target of limiting global warming to no more than 2°C clearly shows that an international agreement in Paris will have to include dynamic mechanisms for the assessment of progress and the raising of ambitions. Hence the Paris summit should not be regarded as just a one-off opportunity to fix targets.”

The authors suggest that countries should focus on four key ways to increase the ambitions of emissions cuts both before and after the Paris summit.

First, hard work over the next few months by all countries to find credible ways of achieving bigger emissions reductions which can be included in pledges to be submitted before the Paris summit, or achieved through additional efforts by partnerships, for example, through specific decarbonisation initiatives among willing countries.

Second, an intensification of efforts to increase investment and innovation, particularly in relation to the development of cities, energy systems and land use, that could help to close the gap between intentions and the goal before and after 2030.

Third, the creation of a mechanism, to be included in the agreement emerging from the Paris summit in December 2015, for countries to review their efforts and to find ways of ramping up the ambition of their emissions reductions by 2030 and beyond.

Fourth, concerted efforts by all countries to build the strong and transparent domestic base necessary for the implementation of their pledges, and so setting them on a path to decarbonisation and enabling them to ramp up their ambitions.